Composts and root pests

[The Tunn]

An idea from my wife’s Auricula society.
Some members were having trouble with vine weevil and, I think it was the owner of blue leaf plants, told them that she had compost mixed for her by a firm called Gardenscape. Apparently they are able to mix chemicals they can’t sell to the public into the compost, which they then can sell.

As it isn’t a standard mix there is a minimum order, but they will bag it either for collection or delivery to one point.
The Auricula society branch ordered a ton and it seems effective. They were able to specify the mix (loam to gravel etc.) and have since ordered more but with a slightly different ratio.

I’m not able to get to my local BCCS group meetings but I thought I’d post this as maybe some groups would want to investigate as it may be a solution to vine weevil, root mealy problems and a group order might be viable.

I think Gardenscape only operate in the South East but there may be similar firms in other areas.

I have no connection with Gardenscape, so this isn’t an advert (!) but their website is at:
https://www.gardenscapedirect.co.uk/

[juster]

Very interesting, I have never heard of anything like this, thanks!

[Terry S.]

One of the formulations of the late lamented imidicloprid was in the form of granules intended for incorporation into composts. Although banned from outside use because of its supposed effect on bees, imidicloprid is still theoretically allowed for use under glass. Maybe this is what is being incorporated into the compost?

[Conrad]

Sounds like a very good idea, a real shame they don't deliver more widely. I've done a bit of googling and can't seem to find an alternative supplier for the south west who can do the same - any suggestions much appreciated!

[ragamala]

One of the formulations of the late lamented imidicloprid was in the form of granules intended for incorporation into composts. Although banned from outside use because of its supposed effect on bees, imidicloprid is still theoretically allowed for use under glass. Maybe this is what is being incorporated into the compost?

It's disappointing to hear you using the word "supposed" in describing effect on bees. This indicates to me either you have a view based on ignoring science, or bias, or simply not having researched enough. Or maybe it is me, seeing so much science denial these days, on small and big issues such as climate change. If I am oversensitive I apologise.

I fully accept that bans imposed on commercial use of chemicals scientifically assessed to be ecologically damaging should not be automatically extended to amateur use in restricted environments where effect may be minimal or zero, or at least un assessed. But it seems to me crystal clear that the decision to ban commerical use of imidocloprid was correct and based on sound scientific reports.

[el48tel]

I don't think it's so much "denial" as "greasing". We bumble along from month to month hearing counter proposal after counter proposal. IMHO it comes down to who funded the research and how much bakshish is available for promotion or to hide the facts.

[Chez2]

I have some large tubs and troughs which I treat for Vine weevil. Its impossible to find the really concentrated stuff I used to use but I have found other solutions available to the public which you dilute with water and water on to your pots.

[Terry S.]

Ragamala: I do actually have a science Ph.D. which is probably why I have a natural scepticism. I wonder how many original papers on imidicloprid you have read, I have actually read zero. Most of our science comes to us second or third hand from people called journalists. Furthermore in most cases, they will not have read the original papers either, but rely on press releases from various universities and other organisations. The original scientists who did the work would have been very careful in analysing their conclusions, but once it gets into the hands of publicists, things change!

Biological systems are very complex and it is extremely difficult and sometimes impossible to disentangle all of the variables. This is one of the reasons why "climate change" has developed into a major industry. There is solid fact: the temperatures on the Earth are on the rise, yes climate is changing. But trying to work out how different factors contribute to this is very challenging.

[The Tunn]

I didn't mean to start debates on insecticide bans or climate change, however interesting they might be! I'm not sure what insecticide Gardenscape use but I'm sure they'd tell anyone who is interested - they are obviously not not doing anything that contravenes current legislation.
I think the issue arose with the Auricula society after the demise of Pravado vine weevil killer, which I understood at the time was a commercial decision rather than one based on the banning of any of the ingredients. The alternative Bug Clear is nowhere near as effective. As an unscientific experiment I sprayed a vine weevil grub with Pravado: dead in five seconds and another with bug clear: still moving after four minutes and finished with a boot.
I'm also not sure whether the chemical used by Gardenscape has a systemic action, which may have an effect on bees; or works by contact in which case only leaf cutters have to worry!
Sorry I don't know much! I've borrowed a few scoops of my Wife's compost to mix with added grit etc. and use with plants that have had root mealy but as they've already been treated with meths, root washes etc. that won't be conclusive. I put it on here in case any groups (or individuals with large collections!) wanted to investigate further if they thought it worthwhile. They seem very helpful at Gardenscape so I'm sure they could answer any queries or concerns over chemicals used, minimum orders, deliveries, etc.

[Terry S.]

Yes, sorry, I'll get back to the science! The brand names of pesticides have become meaningless because the producers keep changing the active ingredient or even use different ingredients for different products within the same range. So one actually has to have a look at the name of the chemical in the small print. If it ends in "prid" then it is a neonicotinoid and has some residual and systemic action such that it can be used as a soil drench (or incorporated into the compost) for longish-lasting effect. If it ends in "thrin" then it is a synthetic pyrethroid that works by contact only. Those are the only two chemical control classes currently available legally to amateurs.

Don't forget that we have an easy-to-use biological control for vine weevil in the form of nematodes. They can't escape like the mealy bug predators do!